Ответ:

а) Сравним значения дробей: \(\frac{11}{650}\approx0{,}017\), \(\frac{9}{65}\approx0{,}138\), \(\frac{21}{50}=0{,}42\).

б) \(\frac{3}{108}=\frac{1}{36}\), \(\frac{24}{72}=\frac{1}{3}\), \(\frac{45}{90}=\frac{1}{2}\), а \(\frac{1}{36}<\frac{1}{3}<\frac{1}{2}\).

Ответ: а) \(\frac{11}{650},\frac{9}{65},\frac{21}{50}\); б) \(\frac{3}{108},\frac{24}{72},\frac{45}{90}\).